This is the smallest challenge padlock in the world. Base is a KASP 12515. Same size as the ABUS 65/15. This challenge lock is not supposed to be hard.
The lock is called Rinz, named after a college of the creator who gifted him this lock. Rinz is a really tough guy, being a marine-veteran and a fire-fighter, as well as being a coach for kids suffering addiction and severe behavioural disorders. This lock goes out to him. I hope the lock is as hard and fun as he is.